The use of battery power to power electronic devices is well known. Use of batteries enables electronic devices to be utilized when not connected to a stationary power source, such as the alternating current (AC) supplied in standard electrical outlets. However, the demands for power that many of these portable electronic devices can make on the power source is often significant. One such example is the use of an ambulatory pumping device for the administration of intravenous liquids to patients.
The administration of intravenous liquids to a patient is well known in the art. Typically, a solution such as saline, glucose or electrolyte contained in a flexible container is fed into a patient's venous system through a conduit such as a polyvinyl chloride (PVC) tube which is accessed to the patient by a catheter. Many times, the fluid is infused under the forces of gravity, and the rate of flow is controlled by a roller clamp which is adjusted to restrict the flow lumen of the tube until the desired flow rate is obtained.
Flow from the container to the patient also is known to be regulated by means other than a roller clamp. It is becoming more and more common to use an electronically controlled infusion pump. Such pumps include, for example, valve-type pumps. In such devices, a container or bag typically provides for the delivery of the fluid to the tube. A mechanism pinches on the tube using an occluder, and typically a pair of occluders. A plunger, pressing on the tube between the occluders provides the motive force to deliver fluid to the patient. When fluid is delivered to a patient, one of the occluders opens. Different bolus sizes are accomplished by controlling a stroke distance of the plunger. Different flow rates are accomplished by varying the frequency of the operation of the occluders and plungers open/close cycle.
Because of the demands such electronic devices place on the power source, the use of a battery pack having sufficient power can add considerable to the cost of the device. In addition, the size and weight of sufficient battery packs can detract from the portability of the device. What is thus needed is a battery pack that incorporates cost-effective, accurate use of multiple batteries.